Switching Regulator Control Circuit Synchronization
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Solution Overview
Problem
Switching regulators with constant on-time systems face challenges in synchronizing multiple channels, leading to increased input current and electromagnetic interference (EMI) due to difficulties in maintaining synchronization of switching signals across channels.
Innovation Solution
A switching regulator control circuit that includes a first and second switching signal generating circuit, where the second circuit adjusts its on-time to synchronize with the first circuit's frequency, preventing simultaneous switching and reducing EMI by detecting lapse times and adjusting the on-time of the second switching signal to match the first signal's timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If switching signals of multiple channels are turned on simultaneously in a constant on-time system, then each channel can operate with fast load response, but the input current increases instantaneously and EMI increases
Solution Approach 1:
The patent applies preliminary action by detecting the rising edge of the first switching signal and using it to preemptively adjust the on-time of the second switching signal before simultaneous switching occurs. The lapse time detection circuit measures the time interval from the first switching signal's rising edge, and this information is used in advance to set the second switching signal's on-time, ensuring it will not turn on simultaneously with the first channel, thus preventing input current spikes and EMI before they occur.
2Productivity
If the on-times of switching signals in multiple channels are set to be equal in a constant on-time system, then each channel operates independently with fast response, but the frequencies of the switching signals change as the duty ratio changes making synchronization difficult
Solution Approach 1:
The patent implements feedback by detecting the rising edge of the first switching signal and using this information to dynamically adjust the on-time of the second switching signal. The lapse time detection circuit continuously monitors the time interval from the first channel's switching signal, and this feedback is used to set the second channel's on-time, ensuring that even when duty ratios change, the frequencies remain synchronized and channels operate reliably without simultaneous switching.
Data Source
AI summary
A switching regulator includes a first switching regulator corresponding to a master channel, and a second switching regulator corresponding to a slave channel. The first switching regulator generates first output voltage Vout1 by a constant on-time system in which on-time is constant. On the other hand, the second switching regulator monitors a first switching signal and a second on-time control circuit determines on-time of a second switching signal in accordance with lapse time from the rising time of the first switching signal to the rising time of a second switching signal.